Solar disk gamma-rays emission via synthetic magnetic turbulence canopy from photosphere to low corona
Gamma-ray emission in the GeV-TeV range from the solar disk (observed by Fermi-LAT and HAWC) is likely to arise from collisions of galactic cosmic rays (GCRs) with solar atmospheric plasma. We model the photo-/chromospheric magnetic field with a static, laminar structure of open field lines in the chromosphere increasingly braiding near the solar surface, with a typical scale height of 0.01 solar radii. The height-dependent increase in magnetic turbulence strength is modulated by an exponential scalar function. Employing 3D test-particle numerical simulations (with PLUTO code) and empirical models for hadronic inelastic collisions, we investigate how such distorted magnetic field lines affect the gamma-rays flux by injecting GeV-TeV protons into both laminar and turbulent regions, as a function of the turbulence strength. Our findings show that the turbulent magnetic structures can account for the gamma-ray spectrum observed by Fermi-LAT/HAWC, in producing a nearly power law dependence on energy. A rebrightening between approximately 30 and 100 GeV (following a yet unexplained $\sim 30$ GeV spectral dip), suggests an enhanced confinement within the photo-/chromospheric layer.
Authors
- Federico Fraschetti (ORCID: https://orcid.org/0000-0002-5456-4771)
Publication Details
- Published
- 2025-09-23
- DOI
- https://doi.org/10.22323/1.501.0648
- Primary Topic
- Solar and Space Plasma Dynamics
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Aeronautics and Space Administration
- Nuclear Safety and Security Commission